This invention relates to a composition including (a) a dopant, (b) a first host having at least one unit of Formula I, and (c) a second host compound. Formula I has the structure where Q is a fused ring linkage having the formula In Formula I: R1 is the same or different at each occurrence and is D, alkyl, aryl, silyl, alkoxy, aryloxy, cyano, vinyl, or allyl; R2 is the same or different at each occurrence and is H, D, alkyl, or aryl, or both R2 are an N-heterocycle; R3 is the same or different at each occurrence and is H, D, cyano, alkyl or aryl; and a is the same or different at each occurrence and is an integer from 0-4.